Print media is absolutely the hardest forum to get a technical, manufacturing or re-manufacturing point across - we struggle with it as well.
Print ads for magazines, trade show brochures, etc. are at the top of the print media pyramid in terms of difficulty.
The best ever? A cassette tape print ad:
Tru-6 is worth it. Why?
It doesn't have to be a picture of your work, just get them to your web site and they will understand what you do.
Getting them to the website is the only reason for your ad. You will tell the technical tale there.
The covers from the magazine you ran where good - think in those terms. Porsche and Ferrari owners are overwhelmingly male. Appeal to that market with a bit of humor and sarcasm.
If I remember correctly, one of the covers had a Dad on a bed looking lovingly at an infant son or daughter. Put an example of your work in place of the baby.
Good luck!